Trapping Indirect Excitons in a GaAs Quantum-Well Structure with a Diamond-Shaped Electrostatic Trap

High, A. A.; Thomas, Anna; Grosso, Gabriele; Remeika, Mikas; Hammack, A. T.; Meyertholen, Andrew; Fogler, M. M.; Butov, L. V.; Hanson, M.; Gossard, A. C.

doi:10.1103/physrevlett.103.087403

Cited by 77 publications

(87 citation statements)

References 20 publications

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“…The repulsive interaction between indirect excitons in the CQW results in the exciton energy enhancement with density. 7,9,10,17,18,20,41,[47][48][49][50][51][52][53] The observed energy enhancement (Fig. 3) indicates that the exciton density increases with increasing P probe .…”

Section: A Experimentsmentioning

confidence: 81%

“…1(a) and 1(b)]. For samples with the same layer structure, designed patterns of top electrodes create the required in-plane potential landscapes for excitons, including traps, 20 lattices, 18,23,29 ramps, 30 and circuit devices. 14,15,19,21 In this work, we use a top electrode unstructured on a large area.…”

Section: Azimuthal and Radial Fragmentation Of The Inner Ringmentioning

confidence: 99%

“…Transport of indirect excitons was studied in a variety of potential landscapes created by applied electric fields, including ramps, 4,11,12,30 traps, 20 lattices, 18,29 moving lattices-conveyers, 23 narrow channels, 16,19,25 and circuit devices, 14,15,19,21 as well as in optically induced traps. 10,13,24,27 A set of exciton transport phenomena was observed, including the transistor effect for excitons, 14,15,19,21 localizationdelocalization transition in random potentials 7,9,10,13,17,22 and in static and moving lattices, 18,23,29 and the inner ring in emission patterns.…”

Section: Introductionmentioning

confidence: 99%

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Pattern formation in the exciton inner ring

et al. 2013

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We report on the two-beam study of indirect excitons in the inner ring in the exciton emission pattern. One laser beam generates the inner ring and a second weaker beam is positioned in the inner ring. The beam positioned in the inner ring is found to locally suppress the exciton emission intensity. We also report on the inner ring fragmentation and formation of multiple rings in the inner ring region. These features are found to originate from a weak spatial modulation of the excitation beam intensity in the inner ring region. The modulation of exciton emission intensity anticorrelates with the modulation of the laser excitation intensity. The three phenomena-inner ring fragmentation, formation of multiple rings in the inner ring region, and emission suppression by a weak laser beam in the inner ring-have a common feature: a reduction of exciton emission intensity in the region of enhanced laser excitation. This effect is explained in terms of exciton transport and thermalization.

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Section: A Experimentsmentioning

confidence: 81%

Section: Azimuthal and Radial Fragmentation Of The Inner Ringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pattern formation in the exciton inner ring

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“…Finally, in the spatially separated 31,32 continuous wave pumping regime cooled (charge compensated 33 ) excitons flow to the studied area of the QW. They can be cooled additionally by evaporative techniques 34 . Due to the persistent inflow of cooled excitons even the degrees of freedom lowest in energy thermalize after a sufficiently long time 35 .…”

Section: Introductionmentioning

confidence: 99%

Anisotropic superfluidity of two-dimensional excitons in a periodic potential

2017

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We study anisotropies of helicity modulus, excitation spectrum, sound velocity and angle-resolved luminescence spectrum in a two-dimensional system of interacting excitons in a periodic potential. Analytical expressions for anisotropic corrections to the quantities characterizing superfluidity are obtained. We consider particularly the case of dipolar excitons in quantum wells. For GaAs/AlGaAs heterostructures as well as MoS2/hBN/MoS2 and MoSe2/hBN/WSe2 transition metal dichalcogenide bilayers estimates of the magnitude of the predicted effects are given. We also present a method to control superfluid motion and to determine the helicity modulus in generic dipolar systems.

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“…Exciton transport was studied in various electrostatic potential landscapes including circuit devices [12][13][14] , traps 15 , lattices 16,17 , moving lattices -conveyerscreated by a set of ac voltages 18 , and narrow channels 14,19,20 .…”

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confidence: 99%

Transport of indirect excitons in a potential energy gradient

Leonard

Remeika

Chu

et al. 2012

Applied Physics Letters

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We realized a potential energy gradient -a ramp -for indirect excitons using a shaped electrode at constant voltage. We studied transport of indirect excitons along the ramp and observed that the exciton transport distance increases with increasing density and temperature.An indirect exciton in a coupled quantum well structure (CQW) is a bound state of an electron and a hole in separate wells (Fig. 1a). The spatial separation allows one to control the overlap of electron and hole wavefunctions and engineer structures with lifetimes of indirect excitons orders of magnitude longer than those of direct excitons. Long lifetimes of the indirect excitons allow them to travel over large distances before recombination [1][2][3][4][5][6][7][8][9][10] . Furthermore, indirect excitons have a built-in dipole moment ed, where d is close to the distance between the quantum well (QW) centers that allows their energy to be controlled by voltage: an electric field F z perpendicular to the QW plane results in the exciton energy shift E = edF z 11 . These properties allow studying transport of indirect excitons in electrostatically created in-plane potential landscapes E(x, y) = edF z (x, y).Exciton transport was studied in various electrostatic potential landscapes including circuit devices 12-14 , traps 15 , lattices 16,17 , moving lattices -conveyerscreated by a set of ac voltages 18 , and narrow channels 14,19,20 .Several exciton transport phenomena have been observed, including the inner ring in emission patterns 4,6,8,10,21,22 , transistor effect for excitons [12][13][14] , localization-delocalization transition in random potentials 4,6,8 and in lattices 16,17 , and dynamical localization-delocalization transition in conveyers 18 . Exciton transport was also studied in potential energy gradients created by voltage gradients in electrodes 1,7 .In this work, we study exciton transport in a potential energy gradient -a ramp -created by a shaped electrode at constant voltage. We utilize the ability to control exciton energy by electrode shape 23 and design the shape of a top electrode on the sample surface so that a voltage applied to it creates a constant potential energy gradient for indirect excitons in the CQW. The excitonic ramp realizes directed transport of excitons as a diode realizes directed transport of electrons.The advantages of this shaped-electrode-method include the suppression of heating by electric currents in electrodes (such currents may appear in the case when the ramp potential is created by a voltage gradient in the top electrode) and the opportunity to engineer the exciton energy profile along the ramp by designing the electrode shape. We also measure exciton transport in a narrow channel formed by a voltage applied to an electrode stripe of constant width -a flat-energy channel 14,20 .The CQW structure is grown by molecular beam epitaxy. An n + -GaAs layer with n Si = 10 18 cm 3 serves as a homogeneous bottom electrode. A semitransparent top electrode is fabricated by depositing a 100 nm indium tin oxide...

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Trapping Indirect Excitons in a GaAs Quantum-Well Structure with a Diamond-Shaped Electrostatic Trap

Cited by 77 publications

References 20 publications

Pattern formation in the exciton inner ring

Pattern formation in the exciton inner ring

Anisotropic superfluidity of two-dimensional excitons in a periodic potential

Transport of indirect excitons in a potential energy gradient

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